MORELIA, MEXICO
— JUST a week after heralding a new era of democracy in one Mexican state, the monolithic Institutional Revolutionary Party (PRI) has resorted to its old bag of tricks to pull off a dubious electoral triumph in another state. Disregarding well-documented charges of voting fraud and foul play, the PRI-dominated state electoral commission pushed through PRI victories in several legislative districts claimed by the Democratic Revolutionary Party (PRD). Led by Cuauht'emoc C'ardenas, a former PRI governor of Michoac'an State, the center-left coalition claims that the PRI is stealing legislative seats in 10 of the state's 18 districts, to preserve its majority in the state congress.

The controversial election comes at a time when President Carlos Salinas de Gortari is receiving international accolades for conceding defeat in a governor's race for the first time in the ruling party's 60-year history. In Baja California Norte, Mr. Salinas stunned nearly everybody - especially hard-liners in his own party - by acknowledging the victory of businessman Ernesto Ruffo Appel of the right-wing National Action Party (PAN). PRI scored a public-relations coup.

Since 1929, Mexicans have known no other authority than the PRI: The ruling party has supplied everything from seeds and services to land and labor unions. Now, for the first time the people are allowed to witness the transfer of power - however limited - to an opposition party.

But not in Michoac'an. The hotly disputed election here not only tarnishes Salinas's lauded decision in Baja California. But it may throw into doubt the depth of his commitment to democracy and political modernization.

``What we have now is a selective democracy,'' says government critic Adolfo Aguilar Zinser, an occasional C'ardenas adviser. PRI leaders could not afford to lose Michoac'an to the left, he says, because they ``think the Cardenista movement is bound to radicalize the situation.''

Certainly, Salinas seems more willing to cede power to the right-wing PAN, with whom he shares an ideological affinity, than to the PRD, whose populist ideas are antagonistic to his conservative economic program.

Ever since Mr. C'ardenas gave Salinas a scare in last year's presidential election, the PRI has attempted to weaken the left. But the PRI's focus has been Michoac'an, the home of both C'ardenas and his father, former President L'azaro C'ardenas.

Last year, the younger C'ardenas won 63 percent of the vote to Salinas's 24 percent in this state. The PRI responded with the so-called Michoac'an Plan, a public-spending blitz designed to bring voters back to the fold.

Unlike the relatively clean elections of Baja California, charges of fraud permeated Michoac'an. In Apatzingan, a C'ardenas stronghold in last July's elections, the electoral commission nullified three voting booths in which the PRD led, giving the PRI a razor-thin, 300-vote victory margin.

But perhaps the most startling inconsistencies were found in District 1, which covers the northern half of this colonial city.

Just as the district electoral commission began to discuss the 24 most-contested ballot boxes, officials expelled journalists and opposition members who were observing the vote tally in disbelief. It was too late: They had already witnessed dozens of falsified voting sheets.

For instance, all parties confirmed in writing last Sunday that voting booth 6-A in Potzundareo, a village on the outskirts of Morelia, never opened. Nevertheless, the electoral commission produced voting sheets that gave the PRI an improbable victory margin over the PRD: 253 votes to zero.

In numerous other cases, digits were added in front of the PRI's total. With one stroke, for example, a total of 51 PRI votes became 151. But some alterations barely masked earlier numbers.

Outside the electoral commission offices, several hundred angry PRD supporters gathered to defend their vote. They were quickly surrounded by 40 riot police and an equal number of Army troops, who lined the streets and rooftops. PRD candidate Adolfo Mart'inez Cedeno showed results that gave him a 4,000-vote advantage over the PRI candidate.

But when the official results for District 1 were announced Sunday night, the PRI had emerged with a narrow victory, 16,953 to 15,244.

The PRD does not have much leverage to challenge the elections. It has no power to vote on the state electoral commission, which ratifies the results. Of five commissioners, four are from PRI and one from PAN. The PRD's last legal recourse is the electoral college, an antiquated system in which the top five vote-getters ratify their own election. None of the opposition has ever been on the college here.

Beyond that, it's not clear how vigorously the PRD will protest the elections. In a successful effort eight months ago to oust the former governor, leftist groups took over municipal buildings in 58 towns. Some pro-C'ardenas groups have even set up parallel privately funded governments.

The outcry over this election may not be so widespread, but it is potentially volatile. The PRD has announced that its supporters will take over state highways and public offices to protest the fraud.

``If the government doesn't respect the vote, we're going to continue our protest,'' says Jaime Rivera, a PRD official here. ``We're going to do it peacefully, but in a way that prevents the government from functioning.''